package demo.queue;

import java.util.Scanner;

/**
 * @ClassName : ArrayQueueDemo
 * @Description :
 * @Author : JB
 * @Date: 2020-08-16 11:57
 */

//使用数组模拟队列
class ArrayQueue{
    private int maxSize; //表示数组的最大容量(队列的容量)
    private int front; //队列头
    private int rear; //队列尾
    private int[] arr;//存放数据

    //创建队列
    public  ArrayQueue(int arrMaxSize){
        maxSize = arrMaxSize;
        arr = new int[maxSize];
        front = -1; //指向队列头部，分析出front是指向队列头的前一个位置
        rear = -1;  //指向队列尾部，指向队列尾的数据（队列的最后一个数据）
    }

    //判断队列是否已满
    public boolean isFull(){
        return  rear == maxSize-1;
    }
    //判断队列是否为空
    public boolean isEmpty(){
        return  front ==rear;
    }
    //将数组添加到队列
    public void addQueue(int data){
        if(isFull()){
            System.out.println("队列已满！");
            return;
        }
        rear++;
        arr[rear] = data;
    }
    //获取队列的数据,,出队列
    public int getQueue(){
        if(isEmpty()){
            System.out.println("队列为空！");
            return -1;
        }
        front++;
        return arr[front];
    }
    //显示队列所有数据
    public void showQueueData(){
       /* StringBuffer str = new StringBuffer();
        for (int i = front=+1; i < rear; i++) {
            str.append(arr[i]).append(",");
        }
        return str.toString().substring(0,str.toString().length()-1);*/

       //遍历
        if(isEmpty()){
            System.out.println("队列为空，无数据！");
            return ;
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.printf("arr[%d]=%d\n",i,arr[i]);
        }
    }
    //显示队列头数据
    public int headQueueData(){
        //遍历
        if(isEmpty()){
            System.out.println("队列为空，无头数据！");
            return -1;
        }
        return arr[front+1];
    }
}

public class ArrayQueueDemo {
    public static void main(String[] args) {
//测试一把
        //创建一个队列
        ArrayQueue queue = new ArrayQueue(3);
        char key = ' '; //接收用户输入
        Scanner scanner = new Scanner(System.in);//
        boolean loop = true;
        //输出一个菜单
        while(loop) {
            System.out.println("s(show): 显示队列");
            System.out.println("e(exit): 退出程序");
            System.out.println("a(add): 添加数据到队列");
            System.out.println("g(get): 从队列取出数据");
            System.out.println("h(head): 查看队列头的数据");
            key = scanner.next().charAt(0);//接收一个字符
            switch (key) {
                case 's':
                    queue.showQueueData();
                    break;
                case 'a':
                    System.out.println("输出一个数");
                    int value = scanner.nextInt();
                    queue.addQueue(value);
                    break;
                case 'g': //取出数据
                    try {
                        int res = queue.getQueue();
                        System.out.printf("取出的数据是%d\n", res);
                    } catch (Exception e) {
                        // TODO: handle exception
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'h': //查看队列头的数据
                    try {
                        int res = queue.headQueueData();
                        System.out.printf("队列头的数据是%d\n", res);
                    } catch (Exception e) {
                        // TODO: handle exception
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e': //退出
                    scanner.close();
                    loop = false;
                    break;
                default:
                    break;
            }
        }

        System.out.println("程序退出~~");
    }

}
